1. Field of the Invention
The present invention relates to a refrigerant compressor and a refrigeration system incorporating same, for use in, such as, an electric refrigerator and an air conditioner.
2. Description of the Prior Art
Recently, in consideration of the environmental pollution and, particularly, the ozone destruction and the global warming, the use of the chlorine-contained freon (chlorofluorocarbons abbreviated as CFC) has been decided to be regulated worldwidely. In response to this, researches have been actively performed by the associated makers, such as, the refrigerant makers, the refrigeration system makers and the oil makers. As a result of the researches, a refrigerant containing, as a main component, chlorine-free carbon fluoride, particularly, known as HFC-134a (hereinafter referred to as "HFC-134a refrigerant"), has been widely admitted as an alternative refrigerant for a CFC refrigerant containing chlorine-contained carbon fluoride, particularly, CFC-12 which has been widely used. Further, in view of required solubility with the HFC-134a refrigerant, a lubricating oil containing an ester oil as a main component (hereinafter referred to as "ester lubricating oil") has been developed as disclosed in Japanese First (unexamined) Patent Publications Nos. 3-128991 and 3-128992.
FIG. 14 is a diagram schematically showing a typical conventional refrigeration system 15 as disclosed in Japanese First (unexamined) Patent Publication No. 4-183788. In FIG. 14, the refrigeration system 15 includes a refrigerant compressor 10, a condenser 11, a drier 14, an expansion mechanism 12 in the form of a capillary tube and an evaporator 13, which are hermetically connected by piping as shown. Further, in the refrigeration system 15, the foregoing HFC-134a refrigerant and the foregoing ester lubricating oil are hermetically enclosed for circulation in a direction of an arrow as indicated in FIG. 14.
However, in the foregoing conventional refrigeration system, there has been raised a serious problem that the cooling power of the refrigeration system was decreased while operated for a long time. The reason for this was found as follows:
During production processes of the refrigerant compressor and the evaporator, a solvent is used for washing and a mineral oil is used for assembling so that these organic substances remain inside the refrigeration system even in a small amount. The ester lubricating oil dissolves these organic substances to produce contaminants. These contaminants block or deteriorate the flow of the refrigerant in the capillary tube so as to lower the cooling power of the refrigeration system.
In the circumstances, component parts of the refrigeration system were fully washed using a solvent or a surface active agent, and then the ester lubricating oil was filled in. As a result, an amount of the generated contaminants was reduced. However, the generation of the contaminants in the refrigeration system could not be prevented completely however carefully the component parts of the refrigeration system were washed. Although only a slight amount of the contaminants was generated after the washing, the generated contaminants choked or plugged the capillary tube to increase a flow resistance of the capillary tube so that the cooling power of the refrigeration system is adversely affected. As a result, the lowering of the cooling power could not be avoided in the conventional refrigeration system using the ester lubricating oil.
This means that the conventional refrigeration system can not effectively capture the contaminants generated due to dissolution of the organic substances by the ester lubricating oil.